I have done my initial best to configure the mailing list to support a jobs topic, and I've blogged about how you can turn off or turn on the jobs listings. [1] From the blog:

  The Code4Lib community has also spawned job postings. Sometimes
  these job postings flood the mailing list, and while it is
  entirely possible use mail filters to exclude such postings,
  there is also "more than one way to skin a cat". Since the
  mailing list uses the LISTSERV software, the mailing list has
  been configured to support the idea of "topics", and through this
  feature a person can configure their subscription preferences to
  exclude job postings. Here's how. By default every subscriber to
  the mailing list will get all postings. If you want to turn off
  getting the jobs postings, then email the following command to
  [log in to unmask]:

    SET code4lib TOPICS: -JOBS

  If you want to turn on the jobs topic and receive the notices,
  then email the following command to [log in to unmask]:

    SET code4lib TOPICS: +JOBS

  Sorry, but if you subscribe to the mailing list in digest mode,
  then the topics command has no effect; you will get the job
  postings no matter what.

  Special thanks go to Jodi Schneider and Joe Hourcle who pointed
  me in the direction of this LISTSERV functionality. Thank you!

The LISTSERV topics feature is new to me, and I hope it works as advertised. I think it will.

[1] blog posting - http://bit.ly/1nSCG2u

— 
Eric Lease Morgan, Mailing List Owner